Conventional steam turbines have a large number of blades mounted about the periphery of the rotor against which the incoming steam impinges. The force applied to the blades to cause movement of the rotor is solely the kinetic energy of the incoming steam.
In a multi-stage turbine, stationary deflector blades mounted on the housing are utilized to shift the steam laterally to impinge on successive sets of blades mounted on other rotors on the same shaft.